Multiple gap velocity modulation tube



April 3, 1951 E. TOURATON ET AL MULTIPLE GAP VELOCITY MODULATION TUBES Filed sept. 8, 1947 @Zig I.

5 Sheets-Sheet 1 April 3, 1951 E. 'rouRAToN ET AL 2,547,061

MULTIPLE GAP VELOCITY MODULATION TUBES Filed Sept. 8, 1947 3 Sheets-Sheet 2 INVENTORS EMILE A. Tol/RATON RENE zwoBAoA BY ANNE -MAf?/E GFATSMULLEI? ATTO R N EY April 3, 1951 E. ToURAToN ETAI. 2,547,061

MULTIPLE GAP VELOCITY MODULATION TUBES Filed Sept. 8, 1947 3 Sheets-Sheet 5 The transit channels T1 and T2 in resonator R1, and Ts and T4 in resonator R2, are shown in the form of two truncated conic portions disposed as in the drawing, although use may be made of electrodes of Very different shapes acccrding to the various uses to which the invention is applied, the shape oi the electrodes being only dependent on the condition that they must effect the convergence of the electron beam at the level of the gaps a, b, c and d, e, f.

In order to facilitate the obtaining of this convergence, it is possible to provide electrodes I2, i3, it, i5, io, E'I, i8, i9, that are dimensioned and disposed so as to improve the desired convergence effect.

Electrode E1 has a shape and a potential suitable for effecting a desired spreading or the electron beam.

The mode of operation of devices of this kind is as follows:

During the iirst modulation, when cylindrical cavity resonator R1 comes into resonance, two successive gaps such as a and b are subjected at a given moment to two unidirectional voltages, and the transit time of the electrons from one gap to the next one is a multiple of a period; this results in the effects of the high frequency eld being additive.

On the other hand, in the variant of the guide of rectangular section shown in Fig. 2, two alternating voltages of opposite directions exist at a given moment in two successive gaps, and one same mass m is equipotential, since it is integral with one same face of the guide, and the transit time of the electrons from one gap to the next is then an odd multiple of a half period.

If R is the resistance at the terminals of a modulation space, U the nig-. frequency voltage at the terminals of this space, and n1 the number of gaps, the power furnished to the beam is U2 'ILVE TMZUZ R which is n1 times -greater than when multiple gaps are used.

At the output end, if rr is the resistance at the terminals of a gap, z' the value of the fundamental component of the alternating current, and n2 the number of gaps, the power given up by the beam to the cavity is mm2 times greater than if the beam was braked only once by the high frequency -eld. The gain, when used as an amplifier, is accordingly multiplied by nmz.

This device may also be used in a frequency multiplier tube.

High voltages have been employed, because the number of gaps that it is possible to use is limited by the transit time of the electrons from the first gap to the last one, and accordingly by the speed of travel, which is itself dependent on the voltage.

If, indeed, upon excitation, the distance between the end gaps is too great, the bunching eiected by the modulation in the rst gap begins to have effect, and the alternating component of the thus obtained current acts on the subsequent gaps. This results in a variation of the impedance at the terminals of the last gap, but this is partially corrected by the shape of the gap and of the transit channel in the cavity.

In the catching space, the number of gaps employed is limited by the fact that they must be located at points along the electron beam path where transfer of ultra high frequency energy from the bea-rn to the field in the resonator will be a maximum. The output voltage U2, ci a resonator excited by an electron stream velocity modulated by an input resonator and bunched in a drift space varies with the distance along th-e path of the stream at which the output resonator is excited by the stream. This variation is in accordance with the Bessel function or" the fundamental component of the modulated current.

w8 U1 Jl 2U() Uu In this expression zu is the pulsation of the fundamental component,

s is the distance from the modulation space or gap to the catching space at which the output voltage U2 is excited in the output resonator,

vo is the mean velocity of the electron in the drift space of distance s,

U1 is the modulation voltage,

U0 is the potential of the electrode E1 about the drift space.

The gaps are grouped in such a way as to correspond to points situated in the vicinity of the maximum of the Bessel function.

While we have described above the principles of our invention in connection with specic apparatus, it is to be clearly understood that this description is made only bj Way of example and not as a limitation on the scope of our invention.

We claim:

l. A velocity modulation electron discharge device comprising a source of an electron beam and a collector electrode deiining a beam path, a cavity resonator disposed about said beam path adjacent said source for velocity modulating electrons in the beam, said modulating resonator including a wave guide of rectangular section and masses of parallelepiped shape located along the beam path inside said guide and supported alternately on opposite sides of said guide, said masses being provided with apertures for passage of the beam therethrough, said masses defining therebetween a plurality of gaps along the beam path for permitting an eiectromagnetic field developed in said resonator to velocity modulate the electrons in the beam successively at each said gap, and a cavity resonator disposed about said beam path adjacent :aid collector electrode for extracting ultra high frequency energy from the velocity-modulated electron beam, said extracting resonator being provided with gap for permitting the electron beam to supply energy to an electromagnetic field developed in said extracting resonator.

2. An electron discharge device according to claim i in which energy extracting cavity resonator comprises a wave guide of rectangular section and masses of parallelepiped shape located along the beam path inside said guide and supported alternately on opposite sides of said guide, said masses being provided with apertures for passage of the electron beam therethrough, said masses defining therebetween a plurality of gaps along said beam path for permitting an electromagnetic rleld developed in said resonator to eX- tract energy from the electrons in the beam successively at each said gap.

3. A device as set forth in claim 1 in which the said masses are equal in length in the direction of the beam path whereby the transit time of the electrons from one gap to the next is adjusted to be an odd multiple of a half period of the operating frequency.

4. A velocity modulation electron discharge device comprising a source of an electron beam and a collector electrode defining a beam path, a cavity resonator disposed about said beam path adjacent said source for velocity modulating electrons in the beam, and a cavity resonator disposed about said beam path adjacent said collector electrode for extracting ultra high frequency energy from the velocity-modulated electron beam, said extracting resonator including a wave guide of rectangular section and masses of parallelepiped shape located along the beam path inside said guide and supported alternately on opposite sides of said guide, said masses being provided with apertures for passage of the beam therethrough, said masses defining a plurality of gaps along the beam path for permitting the velocity-modulated electron beam to supply energy to an electromagnetic eld developed in said resonator successively at each said gap.

5. A velocity modulation electron discharge device comprising an electron beam source and a collector electrode defining a beam path, a cavity resonator disposed about said beam path adjacent said beam source for velocity modulating electrons in said beam, and a cavity resonator disposed about said beam path adjacent said collector electrode for extracting energy from the velocity modulated electron beam, each of said cavity resonators having means for communication with said electron path, one of said resonators including a Wave-guide section with masses spaced apart along the beam path inside {said guide and supported alternately on opposite sides of said guide, said masses having apertures for passage of the beam therethrough.

6. An electron discharge device according to claim 5, wherein said waveguide section is rectangular in cross-section and said masses are of parallelepiped shape.

EMILE TOURATON. RENE ZWOBADA. ANNE-MARIE GRATZMULLER.

REFERENCES CITED The following references are of record in the iile of this patent:

UNITED STATES PATENTS Number Name Date 2,190,515 Hahn Feb. 13, 1940 2,284,751 Linder June 2, 1942 2,401,945 Linder June 11, 1946 2,405,175 Anderson et al Aug. 6, 1946 2,422,695 McRae June 24, 1947 

